Kernel Panic With 4k 240 Hz External Monitor

I also have exactly the same issue (DCPEXT PANIC) with an MSI MPG321 URX (connected via USB-C) and M2 Max MacBook Pro 14". The regular kernel panics happen only with Sequoia (any version). There were zero crashes with Sonoma, so this is clearly a regression. It seems all monitors with 240Hz Samsung QD-OLED panels are affected.

I already reported this issue via Feedback Assistant in November but I still haven't heard anything back. "Resolution" for the report is still "Open" and "Recent Similar Reports: None". Did any of you report the issue this way? Maybe if more users would file reports in Feedback Assistant, the issue would get more attention from Apple.

I also reported it with Feedback Assistant (in late December), same 'Status' and 'Recent Similar Reports' status as yourself.

Can't personally corroborate the Sequoia vs Sonoma story as I've only used my 240Hz panel with Sequoia, but that's a good detail to note.

Definitely needs more reporting this way, as I get the sense 240Hz panels aren't very popular within the Mac ecosystem, given they'll be primarily used for Windows gaming, so this might be overlooked.

Thunderbolt output is definitely not limited to 60Hz. At 6K the maximum is indeed 60Hz but that is because 6K has much higher bandwidth requirements. These vague specs neither confirm nor deny that higher refresh rates are supported at lower resolutions but in practice macOS does offer up to 240Hz at 4K, so it is actually supported.

Thanks for sharing your experience. This confirms that the issue isn't limited to just M2. M4 Pro seems to behave the same way. The ASUS PG32UCDM monitor has the same Samsung QD-OLED panel as the others mentioned in this thread.

Same issue here.

MacBook Pro

Mac14,6

Z1760002PCH/A

Apple M2 Max

12（8性能和4能效）

64 GB

Firmware 11881.81.4

11881.81.4

every 2-3 days it's crashed with below error messages.

I also connect to the MSI MPG 322URX QD-OLED which is 4K 240MHZ monitor.

I have upgraded to the latest version of the MAC OS 15.3.1, but the issue is still in there.

panic(cpu 1 caller 0xfffffe0032c512ac): DCPEXT1 PANIC - apt firmware: dual_pipe.c:180 sync_pipe_end_of_config() --  - iomfb_mailbox(70)

apt firmware: dual_pipe.c:180 sync_pipe_end_of_config() -- 

RTKit: RTKit-2758.80.3.release - Client: AppleDCP-811.80.8~570-t602xdcp.RELEASE

!UUID: a1000010-2140-1ed5-a178-80d201401ed5

ASLR slide: 0x00000000001b7000

Time: 0x000000c7890cb1bd

Having the same issue on a Mac Studio (M2 Max) connected to a Samsung G93SC DQHD running at 48-240Hz VRR, 5120x1440, which is less demanding than 4K 240Hz. Frequent (daily?) crash and reboot on Thunderbolt - DisplayPort.

I'll downgrade to 120Hz for the moment and watch this thread. At least I know that this is a MacOS bug rather than faulty monitor or Mac.

The words "dual_pipe" in your panic report suggest that a very strange exceptions condition may be happening here.

there is a display, which runs at somewhat higher resolution and 10-bit color, that should not work because its data rate is too fast for Thunderbolt. But it does work because Apple treats it as two displays on one Thunderbolt connection:

The Apple Pro Display XDR, which macOS allows to connect using two HBR3 connections to a Mac, doesn't support Display Stream Compression (DSC). That [total data rate] would be 51.84 Gbit/s, impossible for Thunderbolt 3, but it works because the two 3008×3384 10bpc 60 Hz 648.91 MHz signals of the XDR display only require 38.9 Gbit/s total and Thunderbolt does not transmit the DisplayPort stuffing symbols used to fill the HBR3 bandwidth.

https://en.wikipedia.org/wiki/Thunderbolt_(interface)

perhaps these troublesome displays have been given the same special treatment, and it is not quite working. I recommend contacting support and asking for a specialist to read your panic reports, as I described above.

<< OK, I got some 'good news' here. Been talking to the Apple Support, explaining the situation and just aknowledging.

The person found a 'tracker' about this issue. >>

That is good news not only for THIS ISSUE, but also for Apple Support Specialists -- working as designed.

The mechanism of providing Formal, well-documented Bug Reports to Apple does work. With that information, they can (and do) try to reproduce the issues you are encountering, track down those bugs, and fix them!

[In my opinion] It remains lamentable that the feedback back to the User is so weak, and that problems sometimes take a very long time to fix.

Unfortunately the kernel panic still happens with macOS 15.4. Also, the status of my bug report in Feedback Assistant has been finally updated after many months to: "Investigation complete - Unable to diagnose with current information"... There is no other update, reply or request for further information (but I'm not sure what else could be provided anyway).

At this point I think it's very likely that Apple will never fix this issue because it seems a kernel panic like this isn't considered important enough. Perhaps the reason is that the panic doesn't happen with an Apple device but with a "third-party" one but it's completely unreasonable to expect that everyone should connect only Apple branded devices to their Macs. These high-end monitors are perfectly stable on PCs with Windows and Linux using various GPUs from different vendors.

yes, BUT:

XDR display

The Apple Pro Display XDR, which macOS allows to connect using two HBR3 connections to a Mac, doesn't support Display Stream Compression (DSC). That would be 51.84 Gbit/s, impossible for Thunderbolt 3, but it works because the two 3008×3384 10bpc 60 Hz 648.91 MHz signals of the XDR display only require 38.9 Gbit/s total and Thunderbolt does not transmit the DisplayPort stuffing symbols used to fill the HBR3 bandwidth.

https://en.wikipedia.org/wiki/Thunderbolt_(interface)

It's not relevant here what Apple Pro Display XDR supports. The 4K 240Hz OLED monitors do support DSC, and the Mac can drive them using DSC. There's just a bug in the Mac's DCP firmware which results in an occasional kernel panic.

Though seems less frequently, I just got another episode on Sequoia 15.4.1.

M2 Max Mac Studio paird with Samsung Odessey G9 OLED (G93SC), Displayport, 240Hz VRR @ HiDPI (7680 x 2160 down to 3840 x 1080).

Holy...

this issue is so old and i took me days to figure out what is the issue.

I have 2 Samsung Curved Screens (120 & 240 Hz) the 240 Hz crashes frequently my Mac Studio M3 Ultra.

Core Panic Details:

Panic Type: DCPEXT1 PANIC - apt firmware: dual_pipe.c:295 sync_pipe_end_of_config()

Triggering Task: iomfb_mailbox (Task 69) – RUNNABLE at time of panic

RTKit Firmware: RTKit-2784.120.5.0.1.release

AppleDCP FW: AppleDCP-811.120.12.0.1~680-t603xdcp.RELEASE

macOS Version: 14.5 (Build 24F74)

Kernel Version: Darwin Kernel Version 24.5.0

Panicked CPU: Core 18

Relevant Kernel Extensions (Kexts):

- com.apple.driver.RTBuddy

- com.apple.driver.IOSlaveProcessor

- com.apple.driver.AppleDCP

Backtrace Top:

- sync_pipe_end_of_config() (dual_pipe.c:295)

- DCPEXT1 PANIC

- iomfb_mailbox (Task 69)

same issue too.

System panic when using 4K 240Hz external… - Apple Community